Thread by @gauravsabnis

Somewhat emotional and rambling and sciency 🧵 coming up. 🥲

This here is the first appearance of Autumn red leaves at #OurWawar. Red maple beat out red oak.

Longtime followers will know my obsession with the beauty of Autumn red and the intriguing open science behind it.

As I've tweeted pretty much every October, the Autumn red is a fundamentally different thing than Autumn yellows and orange. And it is not yet a settled question about why exactly some trees go through this trouble of turning red just a couple of weeks of the year.

Pretty yellow leaves, like you see in Europe etc, do not require any extra effort from the trees. And makes total evolutionary sense. Deciduous trees shut down chlorophyll production as the sun grows weaker and heavy snow is about to start. That slowly turns em yellow, brown.

But red leaves are different! For an oak or maple to turn red, the tree has to start a separate production process, creating a chemical that turns them red. For only a week or two until they all fall down. It's an energy intensive process. So what do trees gain from it?

And why does it happen only in North America and a couple of other places? What possible advantage are the trees getting by turning red other than making humans very happy and making it likely that they plant or nurture more of these fleetingly red beauties?

There are theories.

Many of those theories contradict each other and don't explain why it only happens for such a short time. Like attracting animals or deterring animals.

In maples, it seems to have a sun screen type effect. That's currently the most acceptable explanation. But still limited.

Even if maples get UV protection from the red color in that transition phase before they fall, it's still not true in other trees that turn red. And many varieties of these trees thrive without turning red. So what gives?

This is one of my random esoteric obsessions. Thinking about why these trees work so hard to turn red. Most mammals are color blind, or at least RG blind. So they can't tell a red leaf from a white leaf. Bugs, birds see more colors than us. But how does it really affect them?

Maybe there was some bug that only came out these two weeks? But the trees seem to have survived without it. So what gives?

Fun to think about. While admiring the gorgeous fiery reds of the North American Autumn that make it objectively the best Autumn in the world.

/Fin

P.S. I'm not a scientist, just a science enthusiast. So actual experts, please feel free to correct any mistakes or add more fundaes.